Kernel list_head demo实现

内核中很多地方用到队列，如果每一个数据结构都实现一个双向队列，并针对这些数据结构实现对应的操作，那么代码将会非常冗余，于是内核抽象出了list_head数据结构，并文参考内核中的代码写成，实现了一个list_head demo。

#include <iostream>
#include <stdint.h>

using namespace std;

#define list_entry(ptr, type, member) 
    ( (type *) ((char *)(ptr) - (unsigned long)(&((type *)0)->member)))

struct list_head {
    struct list_head *prev, *next;
};

inline void init_list_head (struct list_head *ptr)
{
    ptr->prev = ptr;
    ptr->next = ptr;
}

inline void __list_add (struct list_head *prev, struct list_head *next, struct list_head *node)
{
    prev->next = node;
    next->prev = node;
    node->prev = prev;
    node->next = next;
}

inline void list_add (struct list_head *head, struct list_head *node)
{
    __list_add (head, head->next, node);
}

inline void __list_del (struct list_head *prev, struct list_head *next)
{
    next->prev = prev;
    prev->next = next;
}

inline void list_del (struct list_head *node)
{
    __list_del (node->prev, node->next);
}

struct page {
    int32_t id;
    struct list_head lru;
    page(int32_t pid) : id(pid) {}
};


struct list_head pageLRUList;

int main ()
{
    init_list_head(&pageLRUList);

     int i;

    for (i = 0; i < 3; i++) {
        struct page *tmpPage = new struct page(i);
        list_add(&pageLRUList, &tmpPage->lru);
    }

    struct list_head *tmpPtr = &pageLRUList;
    for (i = 0; i < 3; i++) {
        tmpPtr = tmpPtr->next;
        struct page *tmpPage = list_entry(tmpPtr, struct page, lru);//(struct page *)((char*)(tmpPtr) - (unsigned long)(&((struct page*)0)->lru));
        cout << tmpPage->id << endl;
    }

    return 0;
}

#后记，很久没有写博客了，之前在点点，lofter有写技术博客，但是发觉并不是太好，又辗转至此。